Referring now to FIGS. 6 and 7, there is illustrated an exemplary embodiment, of a front side of the brazing tabs 132 and a back side of the tab 134 configured with a constraining system for precluding undesired migration of molten brazing material from a position between adjacent ones of the brazing tabs. The tabs 132 and 134 may be provided with constraining grooves 150 formed in outer surfaces of the brazing tabs 132 and 134. The grooves may be spaced around outer peripheries 152 of the tabs 132 and 134 and may be oriented substantially orthogonally to the outer peripheries 152. In an exemplary embodiment, the grooves 150 may be stamped or embossed into the outer surfaces of the brazing tabs 132 and 134. The grooves 150 may be about 0.002 inches to about 0.005 inch deep, 0.010 inch to about 0.020 inch long and about 0.005 inch to about 0.008 inch wide. When molten brazing material flows across a surface of one of the tabs 132 or 134 and approaches the outer periphery 152 of the tab, the grooves 150 may wick the molten brazing material and thus preclude migration of the molten material beyond the outer periphery 152. The grooves 150 may be spaced sufficiently close to one another so that wicking action may occur. The grooves 150 may be long enough and deep enough so that they may effectively act as reservoirs for excess molten brazing material.